Animalia I Invertebrates

8/2/2019 Animalia I Invertebrates

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ANIMALIA I

INVERTEBRATES:SPONGES THROUGHECHINODERMS


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Animal Classification Scheme


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A. Porifera (sponges)

no true tissues exhibit asymmetry or

radial symmetry

aquatic (mostly marine)

most are suspension (filter) feeders

reproduce sexually (gametes) orasexually (budding, fragmentation)

some producegemmules-resist dryingout & extreme temps

Intracellular digestion: happens within the actual cell


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B. Cnidaria (jellyfishes, hydras, corals& sea anemones)

diploblastic ectoderm (epidermis) endoderm (gastrodermis)

exhibit radial symmetry aquatic (mostly marine) Predators: extracellular digestion. They have a cavity, use Enzymes to break food down, and absorb the nutrients. Incomplete, a second Hole never opens up. Lets to a pouch.

two body forms polyp (sessile) medusa (free-swimming)


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Cnidarian life cycle


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many have cnidocytes(stinging cells)

Gland cells secrete enzymes. Interstitial cells are space filler cells. Cnidocytes are cells that

sting.


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many exhibit alternation of generations


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C. Platyhelminthes (planaria, flukes &tapeworms)

triploblastic

unsegmented

acoelomate bilateral symmetry

free-living [planaria] or parasitic [the

rest] (humans & domestic animals) lophotrochozoans


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exhibit cephalization

possessprotonephridia(flame cells)

digestive system (ifpresent) is incomplete

reproduce asexually

(fragmentation) orsexually most are

hermaphroditic


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D. Mollusca 2nd largest group (clams,snails, slugs, octopuses & squids)

Triploblastic- three germ layers

unsegmented exhibit bilateral symmetry

aquatic & terrestrial

possess all organ systems:excretory,reproductive, respritory, etc.

lophotrochozoans


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reproduce sexually (separate sexes) have trochophore larvae They will all have a foot, which helps in locomotion. They all have a specialized epidermis called the

mantle, which helps them exchange gases. They also make the shell, if applicable. They also all havevisceral mass, covered by mantle.


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Mollusk Classification(most common): Bivalves: 2 part hinged

shells (ex. clams) Gastropods: have spiral

or internal shells and acrawling foot (ex. snailsand slugs)

Cephalopods: a modifiedmuscular foot in thehead region (ex. octopusand squid)


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E. Annelida (oligochaetes, polychaetes& leeches)

triploblastic segmented exhibit bilateral symmetry lophotrochozoans aquatic & terrestrial closedcirculatory system reproduce sexually (oligochaetes &

leeches are hermaphroditic)

have trochophore larvae


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F. Nematoda (heartworm, pinworm)

triploblastic

unsegmented

exhibit bilateral symmetry free-living (soil / aquatic) or parasitic

(plants / animals)

digestive system iscomplete

reproduce sexually (separate sexes)

ecdysozoans


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G. Arthropoda triploblastic segmented exhibit bilateral symmetry ecdysozoans exoskeleton composed of chitin opencirculatory system possess Malpighian tubules reproduce sexually have trochophore larvae


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4 subphyla of arthropods:Trilobita (trilobites)- extinctChelicerata (horseshoe crabs, spiders, mites,

ticks, scorpions)

mainly terrestrial 2 major body segments

(cephalothorax & abdomen)

piercing mouthparts 4 pairs of legs

lack antennae


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Crustacea (lobsters, crayfishes, crabs,shrimp)

mainly aquatic

2 or 3 major body

segments possess mandibles

biramous appendages

4 pairs of legs

2 pairs of antennae


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mainly terrestrial possess mandibles

1 pair of antennae uniramous appendages 2 or 3 major body segments insects have wings & 3 pairs of legs millipedes have 2 pairs of legs/segment;

centipedes have 1 pair/segment

Uniramia (insects, millipedes,centipedes)


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H. Echinodermata (starfishes, brittlestars, sea urchins, sand dollars, sea

lilies, sea cucumbers)

triploblastic

deuterostome coelomates adults exhibit radial

symmetry

larvae exhibit bilateralsymmetry


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marine endoskeleton

pedicellariae water vascular system

with tube feet

usually reproduce sexually (gametes);asexually by fragmentation

Similarities in embryonic development &DNA sequences indicate thatechinoderms are closest to thechordates.

Animalia I Invertebrates

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